Imaging apparatus and image sensor including the same

ABSTRACT

An image sensor includes a substrate, thin lenses disposed on a first surface of the substrate and configured to concentrate lights incident on the first surface, and light-sensing cells disposed on a second surface of the substrate, the second surface facing the first surface, and the light-sensing cells being configured to sense lights passing through the thin lenses, and generate electrical signals based on the sensed lights. A first thin lens and second thin lens of the thin lenses are configured to concentrate a first light and a second light, respectively, of the incident lights onto the light-sensing cells, the first light having a different wavelength than the second light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.15/221,719, filed Jul. 28, 2016, in the U.S. Patent and TrademarkOffice, which claims priority from U.S. Provisional Patent ApplicationNo. 62/198,268, filed on Jul. 29, 2015, and Korean Patent ApplicationNo. 10-2016-0044268, filed on Apr. 11, 2016, in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein byreference in their respective entireties.

BACKGROUND 1. Field

Apparatuses and methods consistent with exemplary embodiments relate toimage sensors.

2. Description of the Related Art

Optical sensors including semiconductor sensor arrays may be used inmobile devices, wearable devices, and the Internet of Things. Althoughsuch devices should be small, it is difficult to reduce the thicknessesof imaging apparatuses included in these devices.

Also, as demand for a 3-dimensional image sensor to be used in theInternet of Things, game devices, and other mobiles has increased, anoptical system capable of controlling pathways of light incident ontothe 3-dimensional image sensor is needed. However, because aconventional 3-dimensional image sensor includes complicated opticallenses, it has been difficult to manufacture an appropriate3-dimensional image sensor for use in such devices.

SUMMARY

Exemplary embodiments may address at least the above problems and/ordisadvantages and other disadvantages not described above. Also, theexemplary embodiments are not required to overcome the disadvantagesdescribed above, and may not overcome any of the problems describedabove.

Provided are image sensors that may be configured to have a small sizeand may be configured to obtain 3-dimensional information about anobject.

According to an aspect of an exemplary embodiment, an image sensorincludes an image sensor includes a substrate, thin lenses disposed on afirst surface of the substrate and configured to concentrate lightsincident on the first surface, and light-sensing cells disposed on asecond surface of the substrate, the second surface facing the firstsurface, and the light-sensing cells being configured to sense lightspassing through the thin lenses, and generate electrical signals basedon the sensed lights. A first thin lens and second thin lens of the thinlenses are configured to concentrate a first light and a second light,respectively, of the incident lights onto the light-sensing cells, thefirst light having a different wavelength than the second light.

The substrate may include sub-substrates, and the thin lenses and thelight-sensing cells may be respectively disposed on a first surface anda second surface of each of the sub-substrates.

Each of the thin lenses may include scatterers, and each of thescatterers may have a pillar structure.

An interval distance between a pair of the scatterers may be less than arespective wavelength of light concentrated by a respective one amongthe thin lenses.

A height of the scatterers may be less than a respective wavelength oflight concentrated by a respective one among the thin lenses.

The scatterers may include at least one from among silicon, galliumphosphide, SiC, SiN, and TiO₂.

Shapes of the scatterers and interval distances between respective pairsof the scatterers may vary with a respective wavelength of lightconcentrated by a respective one among the thin lenses.

The image sensor may further include light filters, each of the lightfilters being configured to filter a respective wavelength of lightincident on a respective one among the light-sensing cells.

The image sensor may further include an image synthesizer configured togenerate a multi-color image by synthesizing images of different colors,and at least two among the light-sensing cells may produce the images ofdifferent colors.

The image sensor may further include an image synthesizer configured togenerate a stereo image based on images that are produced by thelight-sensing cells.

The image synthesizer may be further configured to extract depthinformation about an object appearing in the stereo image.

According to an aspect of an exemplary embodiment, an image sensorincludes a substrate, thin lenses disposed on a first surface of thesubstrate and configured to concentrate lights incident on the firstsurface, and light-sensing cells disposed on a second surface of thesubstrate, the second surface facing the first surface, and thelight-sensing cells being configured to sense lights passing through thethin lenses, and generate electrical signals based on the sensed lights.A first thin lens and second thin lens of the thin lenses may beconfigured to concentrate a first light and a second light,respectively, of the incident lights to have different focal lengths.

The substrate may include sub-substrates, and the thin lenses and thelight-sensing cells may be respectively disposed on a first surface anda second surface of each of the sub-substrates.

The concentrated lights may have predetermined wavelengths.

Each of the thin lenses may include scatterers, and each of thescatterers may have a pillar structure.

An interval distance between a pair of the scatterers may be less than arespective wavelength of light concentrated by a respective one amongthe thin lenses.

A height of the scatterers may be less than a respective wavelength oflight concentrated by a respective one among the thin lenses.

Shapes of the scatterers and interval distances between respective pairsof the scatterers may vary with a respective wavelength of lightconcentrated by a respective one among the thin lenses.

The image sensor may further include a depth map calculator configuredto calculate a defocusing degree of an image that is produced on each ofthe light-sensing cells, and calculate depth map information about animage that is produced by the incident lights, based on the defocusingdegree.

The image sensor may further include a light filter layer configured tofilter a wavelength of light incident on each of the light-sensingcells.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will be more apparent by describingexemplary embodiments with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view illustrating an image sensor accordingto an exemplary embodiment;

FIG. 2 is a view illustrating a surface of a thin lens according to anexemplary embodiment;

FIGS. 3A, 3B, 3C, and 3D are perspective views illustrating variousshapes of scatterers according to exemplary embodiments;

FIG. 4 is a view of a surface illustrating a first thin lens accordingto an exemplary embodiment;

FIG. 5 is a view illustrating a surface of a first thin lens accordingto another exemplary embodiment;

FIG. 6 is a view illustrating an image sensor according to an exemplaryembodiment;

FIG. 7 is a view illustrating an image sensor according to an exemplaryembodiment;

FIG. 8 is a view illustrating an image sensor according to an exemplaryembodiment;

FIG. 9 is a view illustrating an image sensor according to anotherexemplary embodiment;

FIG. 10 is a view illustrating an image sensor including a substrateincluding a plurality of sub-substrates, according to an exemplaryembodiment;

FIG. 11 is a view illustrating an image sensor according to an exemplaryembodiment;

FIG. 12 is a view illustrating an image sensor according to an exemplaryembodiment; and

FIG. 13 is a view illustrating an image sensor according to an exemplaryembodiment.

DETAILED DESCRIPTION

Exemplary embodiments are described in greater detail below withreference to the accompanying drawings.

In the following description, like drawing reference numerals are usedfor like elements, even in different drawings. The matters defined inthe description, such as detailed construction and elements, areprovided to assist in a comprehensive understanding of the exemplaryembodiments. However, it is apparent that the exemplary embodiments canbe practiced without those specifically defined matters. Also,well-known functions or constructions may not be described in detailbecause they would obscure the description with unnecessary detail.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items. Expressions such as “atleast one of,” when preceding a list of elements, modify the entire listof elements and do not modify the individual elements of the list.

In the drawings, the thicknesses of layers and regions are exaggeratedfor clarity. It will also be understood that when a layer is referred toas being “on” another layer or substrate, it can be directly on theother layer or substrate, or intervening layers may also be present.

The terms used in this specification are those general terms currentlywidely used in the art in consideration of functions in regard to theinventive concept, but the terms may vary according to the intention ofthose of ordinary skill in the art, precedents, or new technology in theart. Also, specified terms may be selected by the applicant, and in thiscase, the detailed meaning thereof will be described in the detaileddescription. Thus, the terms used in the specification may be understoodnot as simple names but based on the meaning of the terms and theoverall description.

Throughout the specification, it will be understood that when acomponent is connected to another component, the component may bedirectly connected as well as electrically connected with anotherelement therebetween.

It will be further understood that the terms “comprises” and/or“comprising” used herein specify the presence of stated features orcomponents, but do not preclude the presence or addition of one or moreother features or components. In addition, the terms such as “unit,”“-er (-or),” and “module” described in the specification refer to anelement for performing at least one function or operation, and may beimplemented in hardware, software, or the combination of hardware andsoftware.

Additionally, it will be understood that although the terms “first,”“second,” etc. may be used herein to describe various components, thesecomponents may not be limited by these terms. These components are onlyused to distinguish one component from another.

Descriptions of embodiments below may not be understood as limiting thescope of right, but those easily inferred by one of ordinary skill inthe art may be understood as belonging to the scope or right of theexemplary embodiments. Hereinafter, embodiments will be described indetail by referring to the accompanying drawings for the purpose ofdescribing examples only.

FIG. 1 is a cross-sectional view illustrating an image sensor accordingto an exemplary embodiment.

Referring to FIG. 1, the image sensor according to an exemplaryembodiment may include a substrate 110, a plurality of thin lenses 120a, 120 b, and 120 c that are arranged on a first surface S1, and aplurality of light-sensing cells 130 a, 130 b, and 130 c arranged on asecond surface S1 facing the first surface S1 of the substrate 110. Atleast two from among the thin lenses 120 a, 120 b, and 120 c mayconcentrate lights having different wavelength components on thelight-sensing cells 130 a, 130 b, and 130 c. That is, two or more of thethin lenses 120 a, 120 b, and 120 c may have wavelength selectivity withrespect to different wavelengths.

The substrate 110 may have a plate-like shape. The first surface S1 andthe second surface S2 of the substrate 110 may be substantiallyhorizontally parallel to each other. However, the first surface S1 andthe second surface S2 may not be completely horizontally parallel toeach other and may be obliquely parallel to each other. The substrate110 and the light-sensing cells 130 a, 130 b, and 130 c may be spacedapart from one another with an air layer therebetween. The substrate 110may include a transparent material. As used herein, the term“transparent material” denotes a material having a high lighttransmittance. For example, the substrate 110 may include at least onefrom among Si₃N₄, SiO₂, and a polymer such as PMMA or PDMS. Once a pathof incident light changes at the light-sensing cells 130 a, 130 b, and130 c, the incident light may pass through the substrate 110 and becomeincident on a light sensing layer 130.

Each of the light-sensing cells 130 a, 130 b, and 130 c may includescatterers from among a plurality of scatterers 122 a, 122 b, and 122 c.The term ‘thin-lens’ refers to an optical device that changes a path oflight by a difference in phase delays caused by the scatterers 122 a,122 b, and 122 c included in the thin-lenses, unlike related art opticallens. Accordingly, a thickness of the thin-lens may be hardly limitedcompared to that of an optical lens, and the thin-lens may be configuredto be thin. The scatterers 122 a, 122 b, and 122 c on surfaces of thethin lenses 120 a, 120 b, and 120 c may be configured to resonate lightincident on each of the scatterers 122 a, 122 b, and 122 c. Thescatterers 122 a, 122 b, and 122 c may be configured to appropriatelydelay a transmission phase of the light incident on each of thescatterers 122 a, 122 b, and 122 c.

The scatterers 122 a, 122 b, and 122 c may be arranged on the firstsurface S1 of the substrate 110 to form a desired wave front of lightthat transmits from the first surface S1 of the substrate 110. Also, thethin lenses 120 a, 120 b, and 120 c may change a path of transmittantlight with respect to incident light by modulating a wave front oflight.

At least two from among the thin lenses 120 a, 120 b, and 120 c may beconfigured to concentrate pieces of light having different wavelengthcomponents among the incident light on the light sensing layer 130. Forexample, a first thin-lens 120 a may be configured to concentrate apiece of light having a first wavelength λ₁ among the incident light.Also, a second thin-lens 120 b may be configured to concentrate a pieceof light having a second wavelength λ₂ among the incident light. Also, athird thin-lens 120 c may be configured to concentrate a piece of lighthaving a third wavelength λ₃ among the incident light. However, theseare provided as examples for illustrative purpose only, and embodimentsare not limited thereto. For example, not all of the first to third thinlenses 120 a, 120 b, and 120 c have to concentrate pieces of lighthaving different wavelengths, and two from among the first, second, andthird thin lenses 120 a, 120 b, and 120 c may be configured toconcentrate pieces of light having substantially the same wavelength.

FIG. 2 is a view illustrating a surface of one from among the thinlenses 120 a, 120 b, and 120 c according to an exemplary embodiment.

Referring to FIG. 2, a plurality of scatterers may be arranged on asurface of a thin-lens. A wave form of light transmitted from thethin-lens may depend on a shape, an interval distance, and a shape ofarrangement of the scatterers. When the scatterers are formed on thesurface of the thin-lens as shown in FIG. 2, light transmitted from thethin-lens may be concentrated. That is, the thin-lens shown in FIG. 2maybe configured as a lens having positive refractive power.

FIGS. 3A, 3B, 3C, and 3D are perspective views illustrating variousshapes of the scatterers 122 a, 122 b, and 122 c according to exemplaryembodiments.

Referring to FIGS. 3A through 3D, the scatterers 122 a, 122 b, and 122 cincluded in the thin lenses 120 a, 120 b, and 120 c may have pillarstructures. A shape of a cross-section of the pillar structure may befrom among a circle, an oval, a rectangle, and a square. FIG. 3Aillustrates a scatterer having a pillar structure with a cross-sectionalshape of a circle. FIG. 3B illustrates a scatterer having a pillarstructure with a cross-sectional shape of an oval. FIG. 3C illustrates ascatterer having a pillar structure with a cross-sectional shape of asquare. FIG. 3D illustrates a scatterer having a pillar structure with across-sectional shape of a rectangle. The pillar structure may beappropriately tilted in a height direction.

FIGS. 3A through 3D show examples of shapes of the scatterers 122 a, 122b, and 122 c, but embodiments are not limited thereto. For example, atleast one from among the scatterers 122 a, 122 b, and 122 c may have apolygonal prism shape or a pillar structure with a cross-section havingan “L”-like shape. At least one from among the scatterers 122 a, 122 b,and 122 c may have a multi-layer structure formed of materials withdifferent refractive indexes in a height direction. Also, shapes of thescatterers 122 a, 122 b, and 122 c may not have symmetricity in adirection. For example, a cross-section of the scatterers 122 a, 122 b,and 122 c may have shapes that are non-symmetrical in a horizontaldirection such as, for example, an oval shape. Also, when cross-sectionsof the scatterers 122 a, 122 b, and 122 c differ according to theirheight, the shapes of the scatterers 122 a, 122 b, and 122 c may nothave symmetricity with respect to the height.

The scatterers 122 a, 122 b, and 122 c may have a shape according towavelength selectivity of the thin lenses 120 a, 120 b, and 120 c. Here,the term “wavelength selectivity” refers to each of the thin lenses 120a, 120 b, and 120 c selectively concentrating pieces of light of apredetermined wavelength band on the light sensing layer 130. Forexample, the scatterers 122 a included in the first thin-lens 120 a mayhave a shape appropriate to concentrate pieces of light of the firstwavelength λ₁. In one embodiment, a cross-sectional shape of scatterers122 a and a ratio between a width and a height of the scatterers 122 amay change. Also, scatterers 122 b included in the second thin-lens 120b may have a shape appropriate to concentrate pieces of light of thesecond wavelength λ₂. Also, scatterers 122 c included in the thirdthin-lens 120 c may have a shape appropriate to concentrate pieces oflight of the third wavelength λ₃. At least two from among the first,second, and third wavelengths λ₁, λ₂, and λ₃ may be different from eachother.

FIG. 4 is a view illustrating a surface of the first thin-lens 120 aaccording to an exemplary embodiment.

In FIG. 4, the first thin-lens 120 a is used as an example, but thedescription with reference to FIG. 4 may be applied to the second andthird thin lenses 120 b and 120 c.

Referring to FIG. 4, the scatterers 122 a having pillar structures maybe arranged on the substrate 110. In FIG. 4, the scatterers 122 a havecircular pillar structures as an example, but embodiments are notlimited thereto. For example, the scatterers 122 a may have any ofvarious shapes such as polygonal prism shapes, circular cylindricalshapes, or elliptic cylindrical shapes. Alternatively, cross-sections ofthe scatterers 122 a may have “L”-like prism shapes.

A refractive index of a material included in the scatterers 122 a may behigher than a refractive index of a material included in the substrate110. Thus, the substrate 110 may include a material having a relativelylow refractive index, and the scatterers 122 a may include a materialhaving a relatively high refractive index. For example, the scatterers122 a may include at least one from among crystalline silicon (c-Si),polycrystalline silicon (poly Si), amorphous silicon (amorphous Si),Si₃N₄, GaP, TiO₂, AlSb, AlAs, AlGaAs, AlGaInP, BP, and ZnGeP₂. Also, forexample, the substrate 110 may include one from among a polymer such asPMMA or PDMS, Si₃N₄, and SiO₂. An additional clad layer that surroundsand covers the scatterers 122 a having a high refractive index on thesubstrate 110 with the material having a low refractive index may beformed.

The arrangement of the scatterers 122 a may be determined according to awavelength band of light that is concentrated by the first thin-lens 120a. For example, an interval distance T and an arrangement direction ofthe scatterers 122 a included in the first thin-lens 120 a may bedetermined in correspondence to the first wavelength λ₁ of light that isconcentrated by the first thin-lens 120 a. The interval distance Tbetween the scatterers 122 a of the first thin-lens 120 a may be smallerthan the first wavelength λ₁. In one embodiment, the interval distance Tbetween the scatterers 122 a of the first thin-lens 120 a may be ¾ ofthe first wavelength λ₁ or less or ⅔ of the first wavelength λ₁ or less.Also, a height h of the scatterers 122 a of the first thin-lens 120 amay be smaller than the first wavelength λ₁. For example, the height hof the scatterers 122 a of the first thin-lens 120 a may be ⅔ of thefirst wavelength λ₁ or less.

FIG. 5 is a view illustrating a surface of the first thin lens 120 aaccording to another exemplary embodiment.

Referring to FIG. 5, the scatterers 122 a have rectangularparallelepiped shapes and may be arranged on the substrate 110. Althoughthe scatterers 122 a have rectangular parallelepiped shapes in FIG. 5,exemplary embodiments are not limited thereto. For example, thescatterers 122 a may have any shape including polygonal prism shapes,circular cylindrical shapes, and elliptic cylindrical shapes.Alternatively, cross-sections of the scatterers 122 a may have ‘L’-likeprism shapes. Also, heights and interval distances of the scatterers 122a may vary according to a wavelength selectivity of the first thin-lens120 a.

The description of shapes of the scatterers 122 a made with reference toFIGS. 4 and 5 may apply to the scatterers 122 b and 122 c included inthe second and third thin lenses 120 b and 120 c. However, shapes,interval distances, and arrangement directions of the scatterers 122 band 122 c may vary according to a wavelength selectivity of each of thesecond and third thin lenses 120 b and 120 c. For example, intervaldistances and heights of the scatterers 122 b included in the secondthin-lens 120 b may be determined according to the second wavelength λ₂.The interval distances and heights of the scatterers 122 b included inthe second thin-lens 120 b may be smaller than the second wavelength λ₂.Also, interval distances and heights of the scatterers 122 c included inthe third thin-lens 120 c may be determined according to the thirdwavelength λ₃. The interval distances and heights of the scatterers 122c included in the third thin-lens 120 c may be smaller than the thirdwavelength λ₃.

Referring back to FIG. 1, the light-sensing cells 130 a, 130 b, and 130c may be configured to generate electrical signals upon sensing lightthat transmitted from at least one from among the thin lenses 120 a, 120b, and 120 c. The light-sensing cells 130 a, 130 b, and 130 c may beformed in the light sensing layer 130. However, exemplary embodimentsare not limited thereto, and the light-sensing cells 130 a, 130 b, and130 c may be separated from each other.

The light-sensing cells 130 a, 130 b, and 130 c may be prepared incorrespondence to the thin lenses 120 a, 120 b, and 120 c. For example,a first light-sensing cell 130 a may be configured to sense light thatis transmitted from the first thin-lens 120 a. Also, a secondlight-sensing cell 130 b may be configured to sense light that istransmitted from the second thin-lens 120 b. Also, a third light-sensingcell 130 c may be configured to sense light that is transmitted from thethird thin-lens 120 c. The first, second, and third light-sensing cells130 a, 130 b, and 130 c may be configured to receive light and thus mayoutput first, second, and third images, respectively.

Each of the light-sensing cells 130 a, 130 b, and 130 c may includedevices that convert light signals into electrical signals. For example,the light-sensing cells 130 a, 130 b, and 130 c may include CCD sensorsor CMOS sensors. Alternatively, the light-sensing cells 130 a, 130 b,and 130 c may include photodiodes that convert light energy intoelectrical energy.

Because at least two from among the first, second, and third thin lenses120 a, 120 b, and 120 c have different wavelength selectivities, atleast two of the first, second, and third light-sensing cells 130 a, 130b, and 130 c may be configured to measure images in different colors.Therefore, the first, second, and third images measured by the first,second, and third light-sensing cells 130 a, 130 b, and 130 c,respectively, may be synthesized to obtain a multi-color image.

FIG. 6 is a view illustrating an image sensor according to an exemplaryembodiment.

In FIG. 6, a repeated explanation of the same elements or operations asthose in FIG. 1 will not be given.

Referring to FIG. 6, the image sensor according to an exemplaryembodiment may include an image synthesizer 150 configured to synthesizeimages in different colors and thus produces a multi-color image. Theimage synthesizer 150 may synthesize the first, second, and third imagesobtained by the first, second, and third light-sensing cells 130 a, 130b, and 130 c. At least two among the first, second, and third images maybe in different colors. Thus, the image synthesizer 150 may produce amulti-color image by synthesizing the first, second, and third images.The multi-color image may be an image in a plurality of colors. Also,when there are four or more light-sensing cells configured to perform animaging process on four or more different wavelength bands, themulti-color image may be a hyperspectral image.

Because locations of the thin-lens 120 a, 120 b, and 120 c are differentfrom each other, light reflected by an object may be incident atdifferent angles to the thin-lens 120 a, 120 b, and 120 c. Thus, imagesof the object taken from different angles may be obtained from thefirst, second, and third light-sensing cells 130 a, 130 b, and 130 c,respectively. The image synthesizer 150 may produce a stereo image fromthe images of the object taken from different angles. During a processof producing the stereo image, the image synthesizer 150 may extractparallax information among the first, second and third images. Also, theimage synthesizer 150 may be configured to extract depth information ofthe object that is shown in the stereo image.

FIG. 7 is a view illustrating an image sensor according to an exemplaryembodiment.

In FIG. 7, a repeated explanation of the same elements or operations asthose in FIG. 1 will not be given.

Referring to FIG. 7, the substrate 110 may include a plurality ofsub-substrates 110 a, 110 b, and 110 c. The sub-substrates 110 a, 110 b,and 110 c may be formed in correspondence to a respective thin lens ofthe plurality of thin lenses 120 a, 120 b, and 120 c, and a respectivelight-sensing cell of the plurality of light-sensing cells 130 a, 130 b,and 130 c. For example, the first thin-lens 120 a and the firstlight-sensing cell 130 a may be formed on a first and second surface ofa first sub-substrate 110 a, respectively. Also, the second thin-lens120 b and the second light-sensing cell 130 b may be formed on a firstand second surface of a second sub-substrate 110 b, respectively. Also,the third thin-lens 120 c and the third light-sensing cell 130 c may beformed on a first and second surface of a third sub-substrate 110 c,respectively. When the substrate 110 is divided into the sub-substrates110 a, 110 b, and 110 c, interference between pieces of light that areincident on each of the light-sensing cells 130 a, 130 b, and 130 c maybe prevented.

FIG. 8 is a view illustrating an image sensor according to an exemplaryembodiment.

In FIG. 8, a repeated explanation of the same elements or operations asthose in FIG. 1 will not be given.

Referring to FIG. 8, another image sensor according to an exemplaryembodiment may include a plurality of light filters 140 a, 140 b, and140 c, and each light filter in the plurality of light filters 140 a,140 b, and 140 c is configured to filter wavelength components of piecesof light incident on a respective light-sensing cell of the plurality oflight-sensing cells 130 a, 130 b, and 130 c. The plurality of lightfilters 140 a, 140 b, and 140 c may be included in a single light filterlayer 140. However, this is provided herein as an example, and theplurality of light filters 140 a, 140 b, and 140 c may be included inseparate light filter layers from one another. The light filters of theplurality of light filters 140 a, 140 b, and 140 c may be prepared incorrespondence to a respective light-sensing cell of the plurality oflight-sensing cells 130 a, 130 b, and 130 c. For example, a first lightfilter 140 a may filter a wavelength of light incident on the firstlight-sensing cell 130 a. Also, a second light filter 140 b may filter awavelength of light incident on the second light-sensing cell 130 b.Also, a third light filter 140 c may filter a wavelength of lightincident on the third light-sensing cell 130 c.

The first light filter 140 a may allow only a predetermined wavelengthcomponent from incident light to transmit therethrough according to awavelength selectivity of the first thin-lens 120 a. For example, lightof the first wavelength λ₁ from among incident light may transmitthrough the first light filter 140 a, and the first light filter 140 amay allow light of the remaining wavelength components to be reflectedor absorbed. In the same manner, light of the second wavelength λ₂ fromamong incident light may transmit through the second light filter 140 b,and the second light filter 140 b may allow light of the remainingwavelength components to be reflected or absorbed. Also, light of thethird wavelength λ₃ from among incident light may transmit through thethird light filter 140 c, and the third light filter 140 c may allowlight of the remaining wavelength components to be reflected orabsorbed.

FIG. 8 shows an example of the light filters 140 a, 140 b, and 140 cformed at locations where light incident on the thin lenses 120 a, 120b, and 120 c transmit therethrough. However, exemplary embodiments arenot limited thereto. For example, the light filters 140 a, 140 b, and140 c may be formed between the thin lenses 120 a, 120 b, and 120 c andthe light-sensing layer 130. In this case, wavelengths of lighttransmitted through the light filters 140 a, 140 b, and 140 c and thethin lenses 120 a, 120 b, and 120 c may be filtered. In any cases, thelight filters 140 a, 140 b, and 140 c may filter wavelength componentsof light that is incident on the light-sensing cells 130 a, 130 b, and130 c of the light-sensing layer 130, respectively. Because the lightfilters 140 a, 140 b, and 140 c filter wavelengths of incident light, aphenomenon of light of a wavelength band beyond the wavelengthselectivity of each of the thin lenses 120 a, 120 b, and 120 c (where,the phenomenon is also referred to as “optical crosstalk”) may beprevented from being incident on the light-sensing cells 130 a, 130 b,and 130 c. Also, quality of images obtained from the light-sensing cells130 a, 130 b, and 130 c may improve.

FIG. 9 is a view illustrating an image sensor according to anotherexemplary embodiment.

In FIG. 9, a repeated explanation of the same elements or operations asthose in FIGS. 1 through 8 will not be given.

Referring to FIG. 9, the image sensor according to an exemplaryembodiment may include a substrate 210, a plurality of thin lenses 220a, 220 b, and 220 c that are formed on a first surface S1 of thesubstrate 210 and concentrate pieces of light that are incident on thefirst surface S1, and a plurality of light-sensing cells 230 a, 230 b,and 230 c that are formed on a second surface S2 facing the firstsurface S1 of the substrate 210 and generate electrical signals uponsensing light that has transmitted through the plurality of thin lenses220 a, 220 b, and 220 c.

The substrate 210 may include a transparent material. As used herein,the term “transparent material” denotes a material having a high lighttransmittance. For example, the substrate 210 may include at least onefrom among Si₃N₄, SiO₂, and a polymer such as PMMA or PDMS. Once a pathof incident light changes by the thin lenses 220 a, 220 b, and 220 c,the incident light may pass through the substrate 210 and be incident ona light sensing layer 230. The substrate 210, similar to an exemplaryembodiment shown in FIG. 7, may include a plurality of sub-substrates.

FIG. 10 is a view illustrating an example of the substrate 210 includinga plurality of sub-substrates 210 a, 210 b, and 210 c, according to anexemplary embodiment.

Referring to FIG. 10, the sub-substrates 210 a, 210 b, and 210 c may beformed in correspondence to a respective thin lens of the plurality ofthin lenses 220 a, 220 b, and 220 c and a respective light-sensing cellof the plurality of light-sensing cells 230 a, 230 b, and 230 c. Forexample, a first thin-lens 220 a and a first light-sensing cell 230 amay be formed on a first and second surface of a first sub-substrate 210a, respectively. Also, a second thin-lens 220 b and a secondlight-sensing cell 230 b may be formed on a first and second surface ofa second sub-substrate 210 b, respectively. Also, a third thin-lens 220c and a third light-sensing cell 230 c may be formed on a first andsecond surface of a third sub-substrate 210 c, respectively. When thesubstrate 210 is divided into the plurality of sub-substrates 210 a, 210b, and 210 c, interference between pieces of light that are incident oneach of the light-sensing cells 130 a, 130 b, and 130 c may beprevented.

The thin lenses 220 a, 220 b, and 220 c may include a plurality ofscatterers 222 a, 222 b, and 222 c. At least two from among the thinlenses 220 a, 220 b, and 220 c may be configured to concentrate piecesof the incident light on the light-sensing cells 230 a, 230 b, and 230 cto have different focal lengths. For example, the first thin-lens 220 amay concentrate pieces of the incident light to have a first focallength f₁ in a direction toward the first light-sensing cell 230 a.Also, the second thin-lens 220 b may concentrate pieces of the incidentlight to have a second focal length f₂ in a direction toward the secondlight-sensing cell 230 b. Also, the third thin-lens 220 c mayconcentrate pieces of the incident light to have a third focal length f₃in a direction toward the third light-sensing cell 230 c. This isprovided herein as an example only, and exemplary embodiments are notlimited thereto. For example, the first through third thin lenses 220 a,220 b, and 220 c do not necessarily have to concentrate pieces ofincident light to have focal lengths that are all different from oneanother, and two from among the first through third thin lenses 220 a,220 b, and 220 c may concentrate pieces of incident light to havesubstantially the same focal length.

Descriptions of exemplary embodiments provided herein with reference toFIGS. 2 through 5 may apply to surfaces of the thin lenses 220 a, 220 b,and 220 c. The scatterers 222 a, 222 b, and 222 c included in the thinlenses 220 a, 220 b, and 220 c may have pillar structures. Thescatterers 222 a, 222 b, and 222 c may have a shape of a cross-sectionof the pillar structure that may be from among a circle, an oval, arectangle, and a square. Also, the scatterers 222 a, 222 b, and 222 cmay have a polygonal prism shape or a pillar structure with across-section having an “L”-like shape. Shapes of the scatterers 222 a,222 b, and 222 c may not have symmetricity in a direction. For example,a cross-section of the scatterers 222 a, 222 b, and 222 c may have ashape that is not symmetrical in a horizontal direction as, for example,an oval shape. Also, when cross-sections of the scatterers 222 a, 222 b,and 222 c differ according to its height, the shapes of the scatterers222 a, 222 b, and 222 c may be asymmetric with respect to the height.

Shapes of the scatterers 222 a, 222 b, and 222 c may vary depending onfocal lengths of the thin lenses 220 a, 220 b, and 220 c. For example,scatterers 222 a included in the first thin-lens 220 a may have a shapeappropriate to concentrate pieces of light to have a first focal lengthf₁. In one exemplary embodiment, a cross-sectional shape of thescatterers 222 a and a ratio between a width and a height of thescatterers 122 a may change. Also, scatterers 222 b included in thesecond thin-lens 220 b may have a shape appropriate to concentratepieces of light to have a second focal length f₂. Also, scatterers 222 cincluded in the third thin-lens 220 c may have a shape appropriate toconcentrate pieces of light to have a third focal length f₃. At leasttwo from among the first through third focal lengths f₁, f₂, and f₃ maybe different from each other. Also, interval distances among thescatterers 222 a, 222 b, and 222 c and heights of the scatterers 222 a,222 b, and 222 c may differ according to focal lengths of the thinlenses 220 a, 220 b, and 220 c.

When the focal lengths of the thin lenses 220 a, 220 b, and 220 cchange, images that are defocused to different degrees may be formed onthe light-sensing cells 230 a, 230 b, and 230 c. Defocusing degrees ofthe images formed on the light-sensing cells 230 a, 230 b, and 230 c maydiffer according to the focal lengths of the thin lenses 220 a, 220 b,and 220 c and distances between an object and the thin lenses 220 a, 220b, and 220 c. Therefore, when a defocusing degree for each position ofan image measured by each of the light-sensing cells 230 a, 230 b, and230 c is compared with those of images measured by light-sensing cellsand then extracted, distances between the thin lenses 220 a, 220 b, and220 c and the object and a 3-dimensional shape may be obtained.

FIG. 11 is a view illustrating an image sensor according to an exemplaryembodiment.

Referring to FIG. 11, the image sensor may further include a depth mapcalculator 250 that is configured to calculate depth map information ofan image corresponding to incident light. The depth map calculator 250may receive images measured by the light-sensing cells 230 a, 230 b, and230 c. Also, the depth map calculator 250 may recognize a relative blurdegree for each position of the images measured by one from among thelight-sensing cells 230 a, 230 b, and 230 c. Also, the depth mapcalculator 250 may calculate a defocusing degree for each position ofthe images measured by one from among the light-sensing cells 230 a, 230b, and 230 c.

The depth map calculator 250 may calculate depth map information of animage corresponding to the incident light from the defocusing degreemeasured by each of the light-sensing cells 230 a, 230 b, and 230 c andthe focal length of each of the thin lenses 220 a, 220 b, and 220 c. Forexample, the depth map calculator 250 may calculate a distance from eachof a plurality of points on each of objects or a surface of an objectincluded in the image to each of the thin lenses 220 a, 220 b, and 220c. In this regard, as the depth map calculator 250 calculates the depthmap information, the image sensor may obtain a 3-dimensional image ofthe object.

The thin lenses 220 a, 220 b, and 220 c may each concentrate pieces oflight having a predetermined wavelength component. The thin lenses 220a, 220 b, and 220 c may function as an optical device with respect to apredetermined wavelength band of incident light. Shapes, a shape ofarrangement, interval distances, and heights of the scatterers 222 a,222 b, and 222 c included in the thin lenses 220 a, 220 b, and 220 c maybe determined according to wavelength selectivity of the thin lenses 220a, 220 b, and 220 c.

For example, to output an image with one color, all the thin lenses 220a, 220 b, and 220 c may have substantially the same wavelengthselectivity. The thin lenses 220 a, 220 b, and 220 c may all concentratelight of substantially the same wavelength component. Also, shapes, ashape of arrangement, interval distances, and heights of the scatterers222 a, 222 b, and 222 c included in the thin lenses 220 a, 220 b, and220 c may be determined according to focal lengths of the thin lenses220 a, 220 b, and 220 c. Heights and interval distances of thescatterers 222 a, 222 b, and 222 c may be smaller than a wavelength oflight that is concentrated by the thin lenses 220 a, 220 b, and 220 c.

FIG. 12 is a view illustrating an image sensor according to an exemplaryembodiment.

Referring to FIG. 12, the image sensor may include a light filter layer240 that filters wavelength components of light incident on each of thelight-sensing cells 230 a, 230 b, and 230 c. Although the light filterlayer 240 illustrated in FIG. 12 is prepared at a position where thelight incident on the light-sensing cells 230 a, 230 b, and 230 ctravels, exemplary embodiments are not limited thereto. In one or moreexemplary embodiments, the light filter layer 240 may be positionedbetween the thin lenses 220 a, 220 b, and 220 c and the light sensinglayer 230 including the light-sensing cells 230 a, 230 b, and 230 c. Thelight filter layer 240 may allow a predetermined wavelength λ₀ componentamong the incident light to transmit therethrough and may reflect orabsorb the remaining wavelength components. Because the light filterlayer 240 filters the wavelengths of the incident light, noise light ofundesired wavelengths may be prevented from being incident on thelight-sensing cells 230 a, 230 b, and 230 c. Also, quality of imagesobtained from the light-sensing cells 230 a, 230 b, and 230 c mayimprove.

The thin lenses 220 a, 220 b, and 220 c may each concentrate pieces oflight having different wavelengths to have different focal lengths. Forexample, the first thin-lens 220 a may concentrate light having a firstwavelength λ₁ to have a first focal length f₁. The scatterers 222 aincluded in the first thin-lens 220 a may have a shape of arrangementand interval distances appropriate to concentrate pieces of light havingthe first wavelength λ₁ to have the first focal length f₁. Also, thesecond thin-lens 220 b may concentrate light having a second wavelengthλ₂ to have a second focal length f₂. The scatterers 222 b included inthe second thin-lens 220 b may have a shape of arrangement and intervaldistances appropriate to concentrate pieces of light having the secondwavelength λ₂ to have the second focal length f₂. Also, the thirdthin-lens 220 c may concentrate light having a third wavelength λ₃ tohave a third focal length f₃. The scatterers 222 c included in the thirdthin-lens 220 c may have a shape of arrangement and interval distancesappropriate to concentrate pieces of light having the third wavelengthλ₃ to have the third focal length f₃.

Heights and interval distances of the scatterers 222 a, 222 b, and 222 cincluded in the thin lenses 220 a, 220 b, and 220 c may vary accordingto wavelength selectivities of 220 a, 220 b, and 220 c, respectively.For example, interval distances between the scatterers 222 a and heightsof the scatterers 222 a in the first thin-lens 220 a may be smaller thanthe first wavelength λ₁. Also, interval distances between the scatterers222 b and heights of the scatterers 222 b in the second thin-lens 220 bmay be smaller than the second wavelength λ₂. Also, interval distancesbetween the scatterers 222 c and heights of the scatterers 222 c in thethird thin-lens 220 c may be smaller than the third wavelength λ₃.

FIG. 13 is a view illustrating an image sensor according to an exemplaryembodiment.

Referring to FIG. 13, the image sensor may include a light filter layer240 configured to filter wavelength components of light incident on eachof the light-sensing cells 230 a, 230 b, and 230 c. The light filterlayer 240 may include a plurality of light filters 240 a, 240 b, and 240c. The light filters 240 a, 240 b, and 240 c may be applied incorrespondence to the light-sensing cells 230 a, 230 b, and 230 c. Forexample, a first light filter 240 a may be configured to filter awavelength of light incident on a first light-sensing cell 230 a. Also,a second light filter 240 b may be configured to filter a wavelength oflight incident on a second light-sensing cell 230 b. Also, a third lightfilter 240 c may be configured to filter a wavelength of light incidenton a third light-sensing cell 230 c.

The first light filter 240 a may transmit a predetermined wavelengthcomponent among incident light according to a wavelength selectivity ofthe first thin-lens 220 a. For example, the first light filter 240 a mayallow light having a first wavelength λ₁ to transmit therethrough andreflect or absorb light of the remaining wavelength components. In thesame manner, the second light filter 240 b may allow light having asecond wavelength λ₂ to transmit therethrough and reflect or absorblight of the remaining wavelength components. Also, the third lightfilter 240 c may allow light having a third wavelength λ₃ to transmittherethrough and reflect or absorb light of the remaining wavelengthcomponents. Because the light filters 240 a, 240 b, and 240 c filterwavelengths of incident light, noise light of undesired wavelengths maybe prevented from being incident on the light-sensing cells 230 a, 230b, and 230 c. Also, quality of images obtained from the light-sensingcells 230 a, 230 b, and 230 c may improve. Further, the light-sensingcells 230 a, 230 b, and 230 c each generate images in different colors,and thus a multi-color image may be produced by synthesizing the images.

As described above, according to the one or more of the above exemplaryembodiments, an image sensor has been described with reference to FIGS.1 through 13. The image sensor may concentrate pieces of incident lightby using a plurality of thin lenses. In this regard, a size of the imagesensor may be reduced. Also, at least one from among a plurality ofoperation characteristics of the thin lenses may be controlled bychanging at least one from among shapes, a shape of arrangement,interval distances, and sizes of the thin lenses. Therefore, the imagesensor may be easily manufactured. In addition, a 3-dimensional image, amulti-color image, and depth map information of an object may be easilyobtained from imaged generated from a plurality of light-sensing cells.

The foregoing exemplary embodiments are examples and are not to beconstrued as limiting. The present teaching can be readily applied toother types of apparatuses. Also, the description of the exemplaryembodiments is intended to be illustrative, and not to limit the scopeof the claims, and many alternatives, modifications, and variations willbe apparent to those skilled in the art.

What is claimed is:
 1. An image sensor comprising: a substrate; thinlenses disposed on a first surface of the substrate and configured toconcentrate lights incident on the first surface, the thins lensescomprising a first thin lens and a second thin lens; light-sensing cellsdisposed on a second surface of the substrate, the second surface facingthe first surface, and the light-sensing cells being configured to senselights passing through the thin lenses, and generate electrical signalsbased on the sensed lights, wherein the first thin lens and the secondthin lens of the thin lenses are configured to concentrate a first lightand a second light, respectively, of the incident lights onto thelight-sensing cells, the first light having a different wavelength thanthe second light, and wherein each of the thin lenses comprisesscatterers, the scatterers including material having a refractive indexhigher than a refractive index of the substrate.
 2. An image sensor ofclaim 1, wherein the first thin lens and the second thin lens of thethin lenses are configured to concentrate the first light and the secondlight, onto the light-sensing cells with different focal lengths.
 3. Animage sensor of claim 2, wherein the first thin lens comprises firstscatterers disposed on a first surface of the substrate, shapes andarrangement of the first scatterers being configured to concentrate thefirst light of first wavelength with a first focal length, among lightsincident on the first surface, and wherein the second thin lenscomprises second scatterers disposed on the first surface of thesubstrate, shapes and arrangement of the second scatterers beingconfigured to concentrate the second light with a second focal lengthdifferent from the first focal length, among lights incident on thefirst surface.
 4. An image of claim 3, wherein the thin lenses furthercomprises: a third thin lens comprising third scatterers disposed on thefirst surface of the substrate, shapes and arrangement of the thirdscatterers being configured to concentrate the first light with thesecond focal length, among lights incident on the first surface; and afourth thin lens comprising fourth scatterers disposed on the firstsurface of the substrate, shapes and arrangement of the fourth scattersbeing configured to concentrate the second light of second wavelengthwith the first focal length, among lights incident on the first surface.5. The image sensor of claim 4, wherein the first thin lens, the secondthin lens, the third thin lens and the fourth thin lens are respectivelydisposed on a first surface of the each of the sub-substrates, andwherein the light-sensing cells are respectively disposed on a secondsurface of each of the sub-substrates.
 6. The image sensor of claim 4,wherein each of the first scatterers, second scatterers, thirdscatterers and the fourth scatterers includes material having arefractive index higher than a refractive index of the substrate.
 7. Theimage sensor of claim 4, wherein each of the first scatterers, secondscatterers, third scatterers and the fourth scatterers has a pillarstructure.
 8. The image sensor of claim 4, wherein an interval distancebetween two adjacent first scatterers and interval distance between twoadjacent third scatterers is less than the first wavelength.
 9. Theimage sensor of claim 8, wherein a height of the first scatterers andthe third scatterers is less than the first wavelength.
 10. The imagesensor of claim 4, wherein an interval distance between two adjacentsecond scatterers and interval distance between two adjacent fourthscatterers is less than the second wavelength.
 11. The image sensor ofclaim 10, wherein a height of the second scatterers and the fourthscatterers is less than the second wavelength.
 12. The image sensor ofclaim 4, wherein the first scatterers, the second scatterers, the thirdscatterers and the fourth scatterers comprise at least one from amongsilicon, gallium phosphide, SiC, SiN, and TiO₂.
 13. The image sensor ofclaim 4, wherein the first scatterers and the third scatterers aredifferent in at least one of shape or arrangement thereof.
 14. The imagesensor of claim 4, wherein the first scatterers and the fourthscatterers are different in at least one of shape or arrangementthereof.
 15. The image sensor of claim 4, wherein the second scatterersand the fourth scatterers are different in at least one of shape orarrangement thereof.
 16. The image sensor of claim 4, wherein the secondscatterers and the third scatterers are different in at least one ofshape or arrangement thereof.
 17. The image sensor of claim 1 furthercomprising light filters, each of the light filters being configured tofilter respectively the first light of the first wavelength and thesecond light of the second wavelength, among incident lights.
 18. Theimage sensor of claim 1 further comprising an image synthesizerconfigured to generate a multi-color image by synthesizing images ofdifferent colors, wherein the first wavelength and the second wavelengthcorresponds to different color from each other.
 19. The image sensor ofclaim 1 further comprising a depth map calculator configured tocalculate a defocusing degree of an image that is produced on each ofthe light-sensing cells, and calculate depth map information about animage that is produced by the incident lights, based on the defocusingdegree.